Why he matters in this case
Prof. Chase approaches the insulin-evidence problem differently from Dr Adel Ismail. Where Dr Ismail addresses the laboratory assay itself, Prof. Chase addresses the physiology. His published modelling work — developed over two decades of clinical collaboration in neonatal and adult intensive care — asks a direct question: given the Crown’s theory of what was done (insulin added to a TPN bag), and given the baby’s observed glucose and C-peptide pattern, are the reported insulin values physiologically plausible?
His answer: no. The reported insulin values (4,657 pmol/L in one case) are in the range seen in adult attempted-suicide patients who have injected hundreds of units of insulin. They cannot reasonably be produced by the mechanism the Crown proposed.
The physiological-plausibility argument
Prof. Chase’s modelling approach sets up a system-identification problem. Given the inputs the clinical record documents (a TPN bag running at a specified rate, any dextrose infusions, the baby’s weight and metabolic state), and given the outputs the laboratory measured (insulin level, C-peptide, blood glucose trajectory), what insulin input would produce this measured output? The modelling answer for Baby F is that the insulin input required to produce the measured 4,657 pmol/L reading is of a magnitude far in excess of what the Crown’s theory describes (a small-volume spike of exogenous insulin into a slow-running TPN bag).
The point is not that some specific other mechanism is necessarily correct. The point is that the Crown’s own proposed mechanism cannot produce the reading the Crown relied on. A theory that is internally inconsistent with its own numerical evidence cannot support a murder or attempted-murder conviction.
The STAR and SPRINT work
Chase’s clinical-research career has centred on glycaemic control in critically-ill patients. The STAR (Stochastic Targeted) and SPRINT (Specialised Relative Insulin and Nutrition Tables) protocols he co-developed have been used clinically at multiple intensive-care units internationally and are the basis of his detailed physiological understanding of insulin-glucose kinetics in critically-unwell patients, including neonates. His expert opinion on the Letby insulin evidence is therefore not retrospective forensic reasoning — it applies the same quantitative models he has used in active clinical intensive-care practice for over twenty years.
Professional background
- Distinguished Professor, Department of Mechanical Engineering, University of Canterbury, New Zealand. Biomedical engineering; systems-identification for clinical physiology.
- Co-developer (with Prof. Shaw and colleagues) of the STAR (Stochastic Targeted) and SPRINT (Specialised Relative Insulin and Nutrition Tables) glucose-control protocols used clinically in intensive-care units in New Zealand, Europe, and beyond.
- Published widely in peer-reviewed journals on insulin sensitivity modelling, glucose variability, intensive-care glycaemic control, and the analytical limits of clinical-laboratory insulin measurement.
- Principal investigator on multiple research grants on model-based glycaemic control. Doctoral supervisor to researchers working on the intersection of engineering and clinical physiology.
- Engaged with the Letby case as a scientific contributor from 2023-2024 onwards, initially through science4justice.nl and then through direct submissions to the defence and to the Joint Expert Witness Insulin Report process.
Why this biography is on the site
The insulin evidence for Babies F and L is, with the shift-rota chart, the most technically specialist part of the prosecution case. The Joint Expert Witness Insulin Report (May 2025) consolidates the clinical-biochemistry community’s collective position and Prof. Chase’s physiological-plausibility modelling is one of the three load-bearing pillars of that Report (alongside assay-validation work by Dr Adel Ismail and the sample-handling / forensic-lab chain-of-custody work). Readers who want to understand why the Crown’s insulin theory fails on its own numerical evidence will need to understand what Prof. Chase’s modelling shows. This page supplies the context.
Read alongside
- Evidence: the insulin evidence
- Evidence: the Roche Cobas hook effect
- Evidence: the Guildford forensic-laboratory standard
- Evidence: TPN bag chain of custody
- Evidence: blood gases and lactate trajectories
- Dr Adel Ismail — biography
- Prof. Peter Hindmarsh — biography (prosecution insulin expert)
- Dr Sarrita Adams — biography
- Transcript: Panel Joint Insulin Report
- Analysis: Baby F insulin deep dive
Source
University of Canterbury (NZ) Department of Mechanical Engineering faculty profile; peer-reviewed publications on insulin-sensitivity modelling and STAR / SPRINT protocol development; Joint Expert Witness Insulin Report on Babies F and L (May 2025); science4justice.nl commentary referencing Prof. Chase’s input; Panel-published materials and contributors list.